Many commercially important information storage devices include one or more read heads that can read information from rotating disk media (e.g. one or more magnetic or optical disks). Read heads may perform various functions in addition to reading, such as writing information to the disk media, establishing and maintaining a desired physical separation from the disk media, etc. However, for convenience such multifunctional heads will be referred to as a read heads herein. A typical read head includes a slider and a read transducer disposed on a trailing face of the slider. The read transducer is typically part of a merged transducer that may include features and structures to accomplish other functions as well, such as writing, lapping control, heating, and/or microactuation. However, for convenience the entire merged transducer will be referred to as a read transducer herein.
Since the read transducer is much smaller than the slider upon which it is disposed, the entire read head (including both slider and read transducer) is often simply referred to in the art as a “slider,” especially in the context of physical tooling that is used to hold or position the read head. Hence, many structures that are described in the art to hold or support a “slider” are actually used to hold or support an entire read head, including the read transducer that is disposed on its trailing face Likewise, one may describe faces of the read head with terms that are interchangeable with terms used to describe faces of the slider component of the read head. For example, the “air bearing surface” of a read head is the same as the “air bearing surface” of the slider component of that read head. Opposite of the air bearing surface is the top face of the slider or read head. Opposite the trailing face is the leading face of the slider or read head.
The air bearing surface of the read head (i.e. of the slider component of the read head) is typically designed to establish a hydrodynamic lubrication layer known as an “air bearing” between the slider and the rotating disk media. Often the slider is described to be “flying” over the disk media, because it is separated from the disk media by the air bearing. The air bearing is considered to be self-pressurizing since it results from the relative motion between the read head and the disk media, rather than being externally pressurized by any external pressure source. Note that the hydrodynamic lubrication layer is typically referred to in the art as an “air bearing,” and the adjacent slider surface is typically referred to as the “air bearing surface,” even when the surrounding gas (and therefore the hydrodynamic lubrication layer as well) comprises an alternative gas such as helium rather than merely air. For example, although an atmosphere comprising mostly helium is not the same as “air,” the same “air bearing” terminology is used in the art in both contexts for convenience.
Various methods and structures have been disclosed in the art to temporarily hold read heads or “sliders” while they are under test. For example, there have been several disclosures in the art of suspension spring assemblies that include slider clamps or slider sockets that can temporarily hold (and possibly also provide temporary electrical connection to) read heads while under test. Such disclosures include U.S. Pat. No. 6,459,260 to Bonin et al., U.S. Pat. No. 6,903,543 to Boutaghou et al., U.S. Pat. No. 7,719,796 to Takahashi et al., and U.S. Pat. No. 7,643,249 to Motonishi et al.
However, to properly hold the slider during testing, such suspension spring assemblies are necessarily diminutive, compliant, and lightweight, and therefore quite fragile. Consequently, such suspension spring assemblies are easily physically damaged and difficult to use repeatedly as a testing fixture without being damaged. The care in use that is required may be too time consuming for a high volume production-level testing environment. Even while attempting such care, the replacement of such fragile test fixtures may be required too frequently for the fixtures to be practically desirable in such an environment. Hence, although diminutive, compliant, and lightweight suspension springs have been very successful as information storage device components that are intended for one-time assembly, they are not very practical for use as test fixtures that are intended for frequent re-use.
Other methods and structures that have been disclosed in the art to temporarily hold read heads or “sliders” while they are under test, couple a massive component to the slider (that must move with slider). Such coupling of a massive component to the slider can change the dynamic characteristics of the slider/hydrodynamic lubrication layer system (i.e. the so-called “flying” behavior of the slider). For example, the hemispheric base 80 disclosed in U.S. Pat. No. 7,196,512 to Kainuma et al. is more massive than the slider 10 itself, and changes the flying behavior of the slider 10 under test. Such change to the flying behavior of the slider is undesirable since it can affect the read head test results—making the test results different than what would be expected during normal operation of the read head in the storage device.
Therefore, there is a need in the art for a test apparatus that can temporarily hold a read head during testing, that is practically adaptable to a high volume production-level testing environment, and that does not couple a massive component to the slider (that must move with slider).